Nested Nets and Sensor Webs

By
Sam Bacharach

This article is a progress report describing what is
happening with nested geospatial networks and with sensor webs.

Nested Networks
Nested networks are networks built in a layered or hierarchical fashion
using common network interfaces.For example, the USGS' The National Map is a nested
network of geospatial resources that provides a national level view of
several framework thematic layers of the United States.The
National Map is made up of 50 independent state maps.There are 100
counties in North Carolina, about 40 of which have their own maps
online and nested in the state map.Those county maps, by virtue of
being part of the North Carolina map, are also part of The National
Map.For each of those counties, there may be multiple map servers
that each hold some of the constituent map layers, like transportation,
land cover, land use, etc.In The National Map vision,
eventually all the counties in all the United States will be part of The
National Map.When that vision becomes a reality, a national land
use map, for example, will be the combined product and responsibility
of many local officials who have intimate knowledge of their own
county's land use.

The layers in The National Map are accessed via OGC Web Services and the
associated Web services infrastructure provided by other standards
organizations such as the World Wide Web Consortium (W3C) and the Organization for the
Advancement of Structured Information Standards (OASIS).All the
servers implement the OpenGIS Web Map Server Implementation
Specification, so a query submitted through software that implements
that specification can be automatically passed down from one level to
the next.

In the military, nesting would allow for a command or geointelligence
net at the highest level of the command structure, then an overarching
net for each branch of service.Inside the Army, there can be network
layers for corps, divisions, brigades, battalions, etc.down to the
lowest level, which might be a network connecting all the electronics
inside one vehicle.A military network like this won't be on the Web.
It will be a secured intranet, but it will use Web standards, and like The
National Map, it will need OGC standards for discovery of and
access to geospatial data and services.

Consider this example.NATO has released a Request for Tender to design
and build an Enterprise Geographic Services Capability that relies on
OpenGIS interfaces, as illustrated by this graphic taken from the
procurement document.Such an architecture would provide an
international layer above the U.S.military into which it, too, could
nest, using these open interfaces.

Geospatial data at the different levels and from different servers
won't have the same granularity, precision, attributes, etc., but
automatic "rollups" will nevertheless be possible supporting queries to
any level in the architecture.For example, each vehicle and each
soldier in an army unit might eventually have a GPS, and for the first
time in history, a commander at any level in the chain of command would
know - because the coordinates and related attributes are encoded in a
common way - where every soldier and vehicle is.

The network might run in sub-second real time in a tank or between
tanks in a tank battalion, where hardware, software and data are
optimized and tightly controlled.It won't run with such speed and
predictability at higher levels where there is a lot of diversity in
hardware, software and data.Access will be limited to meet security
needs, but any geographic information or geographic processing service
in the whole extended enterprise system can be made available, if the
servers and clients all "speak OGC."

Sensor Webs
The many-layered geospatial network described above will soon have a
new extension: sensor networks.Imagine thousands of sensors -
including imaging devices on satellites, vehicles and humans as well as
fixed meters and gages - all connected to the Web via wireless or wired
technology, all reporting position and other information, all
discoverable through metadata registered in catalogs, all readable
remotely, and some controllable remotely.Engine temperature,
respiration rate, water level, wind speed, radioactivity - virtually
anything that can be gauged or imaged can be on a sensor web.Sensor
webs provide a new means for finding, reading and controlling sensors
on the Web, for acquiring dynamic data layers based on aggregated
sensor inputs, and for automatically generating standards-based
metadata that can be registered to make the data discoverable and
usable.

Standards-based sensor networks will be based on IEEE 1451
specifications and also on OpenGIS Specifications that are emerging
from a five year Sensor Web Enablement (SWE) effort in OGC.Included is
a specification for a standard and straightforward way to characterize
the location and "viewcone" of a video camera.Since April, the SWE
specifications have gone through rigorous testing and improvement in
the third OGC Web Services (OWS-3) testbed, which will conclude with a
final demonstration of capabilities October 18-21, 2005 at SAIC in
Tyson's Corner, VA.

After the demonstration, the SWE specifications will go to the next
step in OGC's consensus process, and we anticipate that they will
become approved OpenGIS Specifications, perhaps within this year.There
is a growing sense of importance and urgency surrounding them, because
they are slotted for roles in at least two Homeland Security
initiatives, described below.

Oak Ridge National Laboratory, an OWS-3 sponsor,
is working with OGC, the National Institute of Standards, the National
Oceanographic and Atmospheric Administration, and the Department of
Defense and others to develop an industry consensus standards platform
- SensorNet - for a comprehensive, vendor-neutral nationwide system for
real-time detection, identification and assessment of chemical,
biological, radiological, nuclear and explosive hazards.

GUARD, a program funded by one of the OWS-3
sponsors, is an initiative to develop an open platform and model that
communities around the country can evaluate and adapt to serve local
homeland security requirements for first responder communications and
decision support.Applications like vehicle tracking, command and
control, and video operate on top of GUARD's two-way wireless broadband
capability for first responders.OGC Web Services, perhaps including
SWE standards, will be among the capabilities they will demonstrate in
the first GUARD demo in Q1 of 2006.

Conclusion
I hope the casual and infrequent observer of OGC will conclude from the
material above that something significant has indeed been going on in
OGC's corner of the geospatial industry.If you are a local official
involved with geospatial information, you can anticipate that The
National Map, GUARD and SensorNet will all become familiar to you
in the next few years.These are manifestations of a maturing National
Spatial Data Infrastructure.